1. Field of the Invention
The present invention relates to an apparatus for a tractor having a rear and front implement attachment mechanism, i.e., devices for the attachment of tools or implements. Each such device has a hydraulic power lift coupled therewith for raising and lowering tools or implements. To actuate the rear power lift as a function not only of measured values, comparison values, and mixed values of the working resistance and the position of an implement or tool and/or of the cylinder pressure, but also of an arbitrary setting or adjustment, the rear power lift is connected with regulating and control elements. The front power lift is connected to a control element for random lifting and lowering of an implement or tool.
2. Description of the Prior Art
With a tractor having a rear implement attachment mechanism, the hydraulic power lift which acts thereon is controlled (by a regulator or controller which controls the pressure-medium supply thereof in conformity with values of position, of the working resistance of an implement, or of the pressure in the lifting cylinder of the power lift, such values being determined at actual value pickups) in such a way that a desired value which is fed to the adjusted or set adjustment feature, such value being for example for the working resistance of an implement, is essentially maintained during operation of the tractor without the assistance of the driver or operator. With some regulators or controllers of this type, it is also possible to mix determined actual values, for example actual values of the position and of the working resistance, in a predetermined or selectable ratio, which is generally known as mixed control.
Furthermore, it is also possible visually to control an implement by hand when this proves useful. Up to now it has been customary to manually control the implements provided for front attachment mechanisms. As a result however, depending upon the type and operation of the implement, and other effects, the driver or operator is from time to time so fully occupied thereby that he must devote his entire attention to guiding or controlling the implement or tool. The addition of a regulator or controller for the front implement attachment mechanism is, however, quite costly, since regulators or controllers of this type, and the corresponding systems, are very expensive.
It is therefore an object of the present invention to improve a tractor of the aforementioned general type, and having a regulatable and controllable rear implement attachment mechanism, as well as a controllable front implement attachment mechanism, without great cost, in such a way that the driver or operator, in addition to the given conditions for arbitrarily influencing the front implement, selectively also has the possibility of controlling or regulating the implement.